Analog and Mixed-Signal Testing: Introduction, Analog Circuit Testing, Mixed-Signal Testing, IEEE Std. 1149.4 Standard f

1. Chapter 11 Analog and Mixed-Signal Testing

2. What is this chapter about? • Introduces AMS circuits, failure modes and fault models. • Addresses analog testing, including DC and AC parametric testing. • Discusses mixed-signal circuits, ADC and DAC, and their testing approaches. • Studies IEEE Std. 1149.4, the standard for mixed-signal test buses

3. Chapter 11Analog and Mixed-Signal Testing • Introduction • Analog Circuit Testing • Mixed-Signal Testing • IEEE Std. 1149.4 Standard for Mixed-Signal Test Bus • Concluding Remarks

4. 11.1 Introduction • Analog Circuit Properties • Analog Defect Mechanism and Fault Models

5. Analog, Digital, and Mixed-Signal Signals 1 0 Mixed-Signal Digital Analog

6. Analog Circuit Properties • Continuous Signal • Large Range of Circuits • Nonlinear Characteristics • Feedback Ambiguity • Complicated Cause-Effect Relationship • Absence of Suitable Fault Model • Accurate Measurements Required

7. Properties - Continuous Signal Digital Signal Analog Signal VOV VH SR VA VL tSettle tLH tHL • Voltage/Current • Slew Rate • Overshoot • Damping Factor • Frequency • Bandwidth • Logic 1, Logic 0 • VIH, VIL, VOH, VOL • Rise Time, Fall Time • Propagation Delay H-L/L-H • Noise Margin High/Low

8. Properties - Large Ranges of Circuits Digital Circuits Analog Circuits • Operation • Current Mode • Voltage Mode • Switching Cap • Structure • Amplifier • Multiplier • Rectifier • Resonator • Operation • Static Logic • Dynamic Logic • Structure • Gates • PLA • Memory

9. Properties- Nonlinear Characteristics • Analog circuits are nonlinear in nature • Nonlinear cause effect

10. - + - + Properties- Feedback Ambiguities • Feedback puts circuit parameters together • Difficult to identify fault location

11. Properties- Complicated Cause-Effect Relationship • Difficult to determine the cause of error.

12. Properties – Absence of Suitable Fault Models Digital Faults • Good Logic Fault Model • Generally Accepted • Stuck-at-1, Stuck-at-0 • Stuck-Open, Stuck-On • Short. Open • Memory Faults • PLA Faults

13. Properties - Absence of Suitable Fault Models • No Good Fault Model • Not Generally Accepted • Open Short • Missing/Extra Devices • Parameter Variation • Performance Deviation • Circuit Structure Related • Functional Faults • ??????????? Analog Faults

14. Properties – Accurate Measurements Required Digital Instrument • Oscilloscope • Function Generator • Logic Analyzer • Frequency Counter

15. Properties – Accurate Measurements Required • Oscilloscope • Function Gen • Freq. Counter • Spectrum Analyzer • Network Analyzer • Impedance Analyzer • Timing Analyzer • Communication Analyzer • RF Instrument • Optical Instrument • Microwave Instrument Analog Instrument

16. 11.1 Introduction • Analog Circuit Properties • Analog Defect Mechanism and Fault Models

17. Defect Mechanisms (1) • Processing Faults • oxide thickness • mobility change • impurity density • diffusion depth • dielectric constants • metal sheet resistance • missing contacts • dust • Material Defects • cracks • crystal imperfection • surface impurities • ion migration

18. Defect Mechanisms (2) • Time-Dependent Failures • dielectric breakdown • electron migration • Packaging Failures • contact degradation • seal leakage

19. Analog Fault Model Defects/Failure Hard Faults Soft Faults

20. Analog Faults - Defect • Defects • Extra Defects • Etching Defects • Source • Dust • Lithography • Layout Oriented • Statistical Model

21. Analog Faults - Hard Faults • Fault Models • Open • Short • Missing Device • Extra Devices • Faulty Effects • Catastrophic Error • Module Malfunction • System Failure

22. Analog Faults - Soft Faults • Parametric Faults • Io: 100uA -> 50uA • W: 20um -> 10um • Deviation Faults • fo: 10MHz -> 5MHz • Gain: 10000 -> 2000 • Sources • Mobility • Oxide Thickness • Impurity Density • Defusion Depth • Dielectric Constants • Metal Sheet Resistance

23. Functional Level Circuit Level Layout Level Analog Fault - Model Mapping • Deviation Faults • Parametric Faults • Extra Defects • Etching Defects

24. Ko Analog Faults - Model Mapping • Layout to Parametric • Defect Statistics • Randomly insert dusts of random size. • Parameter Statistics • Simulate the effect of dust on transistor parameters

25. Analog Faults - Model Mapping • Parametric to Deviation • Use SPICE simulation and statistics to derive the performance deviation. Fto Ko

26. 11.1 Summary • Studied the analog test properties • Nonlinearity, Feedback Ambiguity • No good fault model • Overview the analog test plan • Test Code, Binning, Sequence Control • Focused Calibrations, DIB Checkers • Characterization and Simulation Code • Analog Fault Model • Extra and Etching Defects • Parametric and Deviation faults • Model Mapping

27. 11.2 Analog Circuit Testing • Analog Test Approaches • Analog Test Waveforms • DC Parametric Testing • AC Parametric Testing

28. Analog Testing Spec Oriented Waveform Oriented

29. Specification Oriented Test Analog Devices, Inc.TM

30. Specification Oriented Test • Specification Oriented Test • Check whether all the specs are met • Tedious and inflexible • Example: Operational Amplifier • DC Specifications • Input Offset Voltage • Input Bias Offset Current • Open-Loop Gain • Noise • Common Rejection Ratio • Temperature Drift • AC Specifications • Bandwidth • Harmonic Distortion • Slew Rate • Settling Time • Noise

31. Waveform Oriented Test • Waveform Oriented Test • Compare waveform to the simulated ones

32. Waveform Oriented Test C B D A

33. Analog Testing - Comparison • Specification Oriented Test • Require more test runs and time • Require accurate instrument • Specifications are guaranteed • Low defect level • Waveform Oriented Test • Less test runs and test time • More forgiving on instrument • Specifications are not guaranteed • Low cost

34. 11.2 Analog Circuit Testing • Analog Test Approaches • Analog Test Waveforms • DC Parametric Testing • AC Parametric Testing

35. Analog Test Waveforms Square (Step) Ramp Triangular Sine Chirp (Sweep Sine) Arbitrary Modulated

36. Waveform - Step • For transient response testing • Application: Filter, OPs, VCO, etc • Difficult to generate good steps Tr

37. Waveform - Step • Step change in voltage: Transient testing • Step change in frequency: PLL testing • Step change in amplitude: AGC testing Voltage Step Frequency Step Amplitude Step

38. Triangular Wave Generation - + • Sawtooth Wave Generation Waveform - Ramp

39. Chirp Waveform - Chirp • Also called Sweep Sine • Generation: Triangular to VCO • Application: Frequency response plotting VCO + -

40. Waveform - Chirp • Application: Frequency response plotting CUT Filter VCO LPF + -

41. Waveform - Arbitrary • Synthesized by DACs • Combinations of all kinds of waveform DAC LPF

42. Waveform - Modulated/Synthesized • Modulated/Synthesized Waveforms • Communication System Testing • GSM, CDMA, 1394, USB2, etc. • Modulation • AM, FM, PCM, PWM, QAM, PSK, QPSK • Generated by dedicated instrument

43. 11.2 Analog Circuit Testing • Analog Test Approaches • Analog Test Waveforms • DC Parametric Testing • AC Parametric Testing

44. DC Parametric Testing

45. DC Test – Open-Loop Gain Measurement 80 60 10K 10K 100 10K 40 Ao 20 100 Vi 102 101 103 104 105 106

46. DC Test – Unit Gain Bandwidth Measurement 100 100 1k Inverting Configuration Noninverting Configuration

47. DC Test – Common Mode Rejection Ratio 100 R2 R1 R1 R2

48. DC Test – Power Supply Rejection Ratio

49. 11.2 Analog Circuit Testing • Analog Test Approaches • Analog Test Waveforms • DC Parametric Testing • AC Parametric Testing

50. Analog AC Testing • Test Types • Gain • Phase • Distortion • Signal Rejection • Noise • Test Setup • AGW: Arbitrary Waveform Generator (DAC) • Digitizer: Sample and convert to digital (ADC) CUT AWG Digitizer DSP